Electrical apparatus



May 22, 1928.

1,670,697 E. D. TREANOR ELECTRICAL APPARATUS Filed April 6, 1926 Inventor-:

Edward Dfl'reansr:

Hi$ Attorney Patented May 22, 1928.

UNITED STATES 1,670,697 PATENT OFFICE.

EDWARD D. TBEANOR, 01 PITTSIIELD, IASSACH USETTS, ASSIGNOE T GENERALELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL APPARATUS.

Application filed April 6, 1928. Serial No. 100,153.

My invention relates to electrical apparatus and more particularly tosafety appliances for encased electrical apparatus such as transformersof the type in which the casing is sealed and filled with an inert gasunder heavy pressure. Inert gases such as helium and nitrogen andmixtures of such gases have been proposed for this purpose, the gas orgaseous mixture serving to insulate the electrical apparatus and totransmit the heat generated in the apparatus to its casing whence thisheat is dissipated to the surrounding air. The insulating and heatconducting properties of the gas are improved as its pressure isincreased and pres sures up to ten or more atmospheres have beenproposed. The gas pressure may become excessive and dan erous if itstemperature becomes excessive ue either to an over- ZO load on theapparatus or to accidental fire outside the apparatus casing. On theother hand, the gas pressure may become so low due to leakage from thecasing as to impair its insulating properties to such an extent thatoperation of the apparatus will be unsafe. The general object of theinvention is to provide safety appliances responsive to variations inthe gas pressure and adapted to prevent damage to the apparatus or itscasing\ as a result of the gas pressure reaching ei er an unsafe maximumor an unsafe minimum limit.

Ot r objects and advantages will appear from c following descriptiontaken in connection with the accompanyin drawi which shows the inventionas app ied in connection with a casing filled with gas and containingelectrical apparatus in the form of a transformer.

The particular embodiment of the invention shown in the drawing will bedescribed in connection with a transformer 10 having a casing 11 whichis tightly sealed and filled with a suitable gas adapted to provideinsulation for the transformer and to transmit the heat enerated in thetransformer to the casing w ence it may be dissipated to the surroundingair. The gas is preferably under heavy pressure to improve itsinsulating and heat conducting properties and this pressure may be asgreat as ten or more atmospheres if desired under normal operatingconditions of the transformer.

Within the transformer casing 11 is a cam 12 having an arm 13 connectedto the the transformer lead 22.

movable inner end of a flexible or collapsible member 14, the outer endof this collapsible member being connected by a gas tight joint to thewall of the transformer casing. The

space within the collapsible member 14 com- 80 municates with theoutside air through an opening 15 in the casing wall. The pressure ofthe gas in the transformer casing tends to compress the collapsiblemember 14 but is opposed by a spring 16. It is obvious that a change inthe pressure of the gas will cause the colla sible member 14 to contractor expand and rotate the cam 12 about its pivotal support 17, thedirection in which the cam 12 rotates depending upon whether the gaspressure increases or decreases. The cam 12 normally holds a pivotedlatch 18 in engagement with a spring pressed pin 19. When the gaspressure increases, it will compress the collapsible member 14 againstthe spring 7 5 16 and rotate the cam 12 until, at a predeterminedmaximum pressure of the gas, the lower end of the latch 18 will dropover the end of the cam and release the spring pressed pin 19. Thispermits the pin 19 to be driven forward by its spring against adiaphragm 20 which normally closes an out let in the transformer casing.The diaphragm 20 is of glass or other suitable material adapted to beruptured when struck by the pin 19 so as to permit escape of the gasbefore the pressure in the casin 11 becomes excessively and dangerouslyhigh.

The switch 21 interposed in the transformer lead 22 is normally heldclosed by a pivoted latch 23, the lower end of the latch resting againsta depressed portion of the face of the cam 12. The same motion of thecam 12 which releases the pin 19 also moves the latch 23 to release theswitch 21 and permit it to open, thus disconnecting the transformer andrelieving it of its load.

When the gas pressure in the transformer casing 11 decreases, the spring'16 causes the collapsible member 14 to expand 10 so as to move the cam12 in a direction opposite to that which has just been described. Thismotion of the cam 12 moves the latch 23 so that at a predeterminedminimum gas pressure the switch 21 is released and opens 105 Thus, theswitch 8 21 is opened and the transformer is relieved of its load whenthe gas pressure reaches either a maximum or minimum value outside apredetermined safe range. With an no increasing gas pressure, therupture of the relief diaphragm 20 may occur before or after orsimultaneously with the opening of the switch 21 as desired, dependingupon the shape of the latch controlling surface of the cam 12. After theswitch21 has been opened, it may be reclosed by a plunger 24 extendingthrough the transformer casing and sealed to the casing by a flexible orcollapsible seal 25. The movable contact member of the switch is forcedinto closed position by pressing the plunger 24 against a projection 26on the switch.

A particular embodiment of the invention has been described toillustrate its principics and advantages but it will be understood thatvarious modifications may be made and that the invention is notlimitedby this description except as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. A casing containing electrical apparatus, the casing being sealed andfilled with gas, said casing having a normally closed outlet, means foropening said outlet to permit escape of gas, a" switch connecting saidapparatus to an outside circuit, and'means responsive to the pressure ofsaid gas for controlling the opening of said gas outlet and the openingof said switch.

2. A casing containing electrical apparatus, the casing being filledwith gas, said casing having a normally closed outlet, means for openingsaid outlet to permit escape of gas, a switch connecting said apparatusto an outside circuit, and means responsive to the pressure of said gasfor controlling the opcning of said gas outlet when the gas pressurereaches a predetermined maximum limit and the opening of said switchwhen the gas pressure reaches a. value in either direction outside apredetermined range.

3. A casing containing electrical apparatus, the casing being sealed andfilled with gas, a switch connecting said apparatus to an outsidecircuit, and means responsive to the ressure of said gas for causing theopening of said switch when the gas pressure reaches a predeterminedminimum limit.

4. A casing containing electrical apparatus, the casing being sealed andfilled with gas, a switch connecting said apparatus to an outsidecircuit, and means responsive to the pressure of said gas for causingthe opening of said switch when the gas pressure reaches a value ineither direction outside apredetermined range.

In witness whereof. I have hereto set my hand this 1st day of April.1926.

EDWARD D. TREAN OR.

